The range-extender-equipped BMW i3 explores a strange legal loophole in California. Since its gasoline-powered range is roughly equal to its electric-only range—78 miles on fuel, 72 on battery, per the EPA—the Golden State considers the car a zero-emission vehicle. Credit the i3’s motorcycle-tiny 1.9-gallon fuel tank for that. But in Europe, the i3 can go somewhat further on gasoline, because when European owners fill up, they can cram 2.4 gallons into the tank. And now, some U.S. i3 owners say they’ve found a way to unlock that extra half-gallon of capacity, via a software hack.

Green Car Reports writer John Voelcker brings us the story of some frustrated i3 owners, who’ve apparently unlocked the extra half-gallon of fuel capacity and some additional capabilities using a software cheat code being shared on BMW forums. According to these hackers, the software is the only thing holding back that extra half-gallon, which amounts to around 20 extra miles by forum users’ reckoning. Hey, when your stock tank can’t even hold a full two gallons, every little bit helps.

Other functions that the hacky BMW fans have been able to unlock include a “hold battery charge” mode that conserves battery energy by relying more heavily on the gasoline engine, a feature that’s enabled on European-market i3s and meant to be used when big power demands are upcoming, like a long hill climb. The hackers have also figured out how to enable AM radio, a feature that’s available on Euro-market cars but suppressed in U.S. models due to “negative performance influences of the electromagnetic interference of the electric drivetrain,” as a BMW spokesperson told Green Car Reports.

Of course, poking around in the inner workings of a complex hybrid vehicle’s software is a great way to, at the very least, void your warranty, and bricking your car runs a rather larger risk than, say, accidentally wiping out your smartphone. But if you own an i3 with the range-extender and you’re sick of filling that peanut-sized tank 1.9 gallons at a time, maybe this is just too much temptation to ignore.